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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e31f26669bc400fed3ce5bd6b45f4eca2f4ea9da7fcf1fbc56355bf89bbcd578' 
  AND token = 'MsKwz5xdRD2m64F26N1qiTX8VfyinvKNmCDlMX+1kKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}